Design of a Pilot-Scale Polystyrene Pyrolysis System for the Production of Plastic-to-Fuels (PTF)

Abstract

The accumulation of polystyrene waste poses a critical environmental challenge due to its poor degradability and persistence in natural ecosystems. This study presents the design, construction, and experimental validation of a pilot pyrolysis system for the thermochemical conversion of polystyrene into Plastic-to-Fuels (PTF)-type liquid fuels. A refurbished 20-liter reactor was initially evaluated, identifying limitations in thermal control, vapor venting, and structural safety. Based on this analysis, a horizontal batch reactor made of ASTM A36 steel was designed, optimized to operate at 500°C with a safety factor of 20.5. The system incorporates heating via an LPG burner manifold, a standardized vapor exhaust system, and controlled condensation. Four experimental tests were conducted using feedloads of 150–210 g of polystyrene, achieving conversion yields between 19% and 60% (average 39%), with residence times of 5–7 minutes and maximum pressures of 1.5–3.0 psi. The fuel obtained had an API gravity of 20.0–21.5°, a density of 0.93 g/cm³, and a composition rich in C7–C10 aromatic hydrocarbons. Atmospheric distillation allowed for the recovery of 60% as a light fraction in the range of 140–160°C. The results confirm the technical feasibility of the system for energy recovery from plastic waste, contributing to the development of circular economy technologies in the Ecuadorian context.